FT-IR characterization of Al-rich Li-, Na- and Ca-HMS
Résumé
Starting from a micelle-templated material with Si/Al = 2.5 in the H form, three samples have been obtained by means of partial cationic exchange, with LiCl, NaCl and CaCl2 alcoholic solutions. Their surface properties have been characterized by means of FT-IR spectroscopy of adsorbed probe molecules, namely CO, CO2 and methylacetylene. Spectroscopic results showed that, though having a chemical composition close to that of cations exchanged Y zeolites, such materials exhibit different basic properties: in particular, no carbonate formation has been detected upon CO2 adsorption, ruling out the occurrence of basic oxygens at the surface. These features have been ascribed to the amorphous nature of the walls to be contrasted with the crystalline structure of zeolites.